Method for making ready printing forms



4 Dec.4 21 ,1926. I

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s. A. MCFARLAND 1 METHOD FOR MAKING READY PRINTINGFORMS Filed Nov. 15.1924 2 she-e'us-shewu 1 Dec. 21 ,1926. 1,611,471

s. A.. MGFARLAND METHOD FOR MAKING READY PRINTING FORMS Filed Nov. l5,1924 2 Sheets-Sheet 2 Wil/faim! @wwf/wf.'

Patented Dec. 21,'1926.

FICE.

SAMUEL ANDREWv MCFARLAND, oF OAK PARK, ILLINOIS.

METHOD FOR MAKING READY PRINTING FORMS.

Application filed November 15. 1924. Serial No. 750,184.

My present invention relatesto a method l'or nnlking-ready printingforms. more partieularly to a method for equalizing the iinpression onthe printedfsheet so that every part of the form will show its truevalue and give a clear,` distinct and sharp impression, and theinvention has for its primary object to provide a method for attainingthese endsl that will be more expeditious and that will eti'ect aconsiderable saving in labor and expense in making-ready the Vprintingforms.

Other objects will appear hereinafter.

The invention Consists in the combinations and arrangements of partshereinafter described and claimed. j

\ The invention will be best understood by reference to the accompanyingdrawings forming a part of this specification, and in which, l

F'g. l is a fragmentary view of the noncoated side of an overlay sheet;

Fig. 2 is a similar View of the coated side of au overlay sheet;

Fig. 3 is an enlarged section taken on the line 3-3 o f Fig. 1;

Fig. l shows an enlarged cross sectional view ot an overlay' cutting.machine, this view being taken on the line 4 4 of Fig. 5; and I lFig 5is a front elevational view of an overlay cutting machineiof the typepreferably employed in cutting away the'coating of the overlay sheets.

In making-ready printin'gforms, it is a eommon'pract'ice totrace out thelow spots or impressions on the overlay sheet, and then yto build up thesame by adding sheets to the ,low spots to obtainl an even impression.No form or engraving'is sok perfectly true 40 and level that when inkedin it will show a clear and perfect impression. It is always necessarythat the form be increased at some placesand reduced vat other placesuntil every part thereof shows its true value 5 f clearly, distinctlyand sharply. In order to compensate for 'the inequalities, itis thelcommon practice, as ,already intimated, to add thin sheets to the lowlspots inthe overlay sheet and thereby to` build up until an adequateoverlay is obtain@ Under my improvedimethod, this operation`is`reversed. Instead of building up the low impressions, I make provisionfoil cutting away ,or eliminating the high impressions. In theembodiment of my improved method, .no change in the methods ol preparingthe press cylinder is necessary. .'lhe fox-m is handled the same as forthe ordinary make-ready, care being taken that the cuts K are all typehigh and that the correct amount of packing has been placed on thecylinder or platen. When all is in readiness to pull the. sheet foroverlay, Italie a coated overlay sheet on which the coating ypreferably. is not less than four thousandths and not more than siXthousandths of'an inch in thickness. .This coatedsheet' for overlayshould be of a size large enough to leave a fair margin out-side of theprinting. Usually a sheet having the same vsize or approximately thesame size as the stock that is to be printed will leave sutlicientmargin. On this sheet for overlay, an impression 'is then pulled in theusual way, care,-however, being taken to print on the back of the sheet,that is to say, on the side or face that is devoid of coating. Thevimpression having been thus taken on the non-coated side, it will,wherever too heavy, appear in the form of raised portions on the-coatedside of the overlay sheet. Then in order to compensate for theinequalities in the form, I cut away these raised portions on the-coatedside of the overlay sheet, which raised portions are due as we have seento a too heavy im-v pression, and thereby equalize the impression on theprinted sheet by the amount of the coating remaining on theoverlaysheet.

In the accompanying drawings, I have illustrated by way of example, mypreferred form o f overlay sheet and my preferred form `of machine withwhich to cut away or eliminate the coating of the overlay sheet wherethe impression is too ,heavy In the drawings,4 ItHe-)numeral 6 denotesas 95 a wholean overlay sheet havingr a non-coated side o r face 7andaieoated sideor face 8. A'n impression is pulle fon-the overlay sheetin the` usual wayaysue impression as heref in illustrated resulting linor im ressions indieated tl 9 and the lightand s arp impressi. .11S asindicated at 10.

quate overlay sheet, Itherefore cut away the 110 theztoo heavy linessuitable tools.

raised portions 11 to such an extent asv may tinct impression thatwill'correspond in all respects with the lighter impressions such asindicated at 10. The raised portions 11 ma be cut awayg by hand throughthe use of a s arp knife,.safety razor blade, or other This however is alaborious method by which to cut down the high portions and I preferablyfor this purpose e111- p`loy my improved overlay cutting machine, themain features of which are herein illustrated. f x

This overlay cutting machine includes a base 12 from the opposite endsof which rise end frames 13 in which is journaled for rotation the axisof the overlay supporting cylinder 14. Thisl cylinder is so `ground thatall points of its circumference are equi-distant from Y its axis; and itis referably formed with the opposed end anges 15. Extending'acrosstheface of this c linder is a recess 16 through which exten s a rock shaft17 which has its opposite ends rotatably mounted in the cylinder flanges15. Mounted on this rock shaft is a series of spaced-apart grippers 18'which are adapted' to bind upon the c linder the edge of the overlaysheet 6/whic is applied with its noncoated side engaging the cylinder.Spring members 19 coiled Iabout the rock shaft and engagin with thecylinder, normally urge ,the roc shaft into position toV have. the

pun

' of w ich the c linder may be manuali fre-A the.

' justin nec , grippers binding the overlay sheet to the cyhnderasillustrated in Fi 5. One end of the rock shaft is provide with a crank20 carryin a roller 2 1 which, during the rotation o the cylinder,engages with a cam 22 so as to raise the rock shaft automatically vforthe release of the overlay sheet.

As soon as the roller 21 is disengaged from Y the cam 22 the rock shaftis automatically turned again to `bring the grippers into grippingposition..

The cylinder is revolved'by means of a pulley 23 spelt therefor notshown) which 1s fast on t also has a hand crank 25 by means volved.'Fort el purpose of cutting o raised portions on the overla sheet themauipped with cutting tools 26 of shown; Each of these cutting tools hasa plurality of spirally vextending 'knives lor lades 27, Eachcof thesecuttingtools has 'an axis .28, the opposite ends of which are su portedin journal boxes 29 which are slid 'm ab y arranged in the end fra-m'es30 which frames 13 as lshown in Fi 5. Each of the 'rises from' the -baseat theA inner sides of the journal'boxes has combi therewithanadscrewlwhich Ais operatively' conin the end frame and which carries. aknxirled disc 32 whereby operated' by e axis'24 ofthe cylinder. This nhand. These cutting tools, therefore, are be necessary to produce alevel,cleai`and dis- A supported about the cylinder in parallelismcylinder and each of thd cutting tools, inorei over is adjustableindependently of the others. As .clearly shown in Fig. 5 one ,of thecutting tools may have its cutting knives 27 coursing in a spiraldirection that is opposite to the directions of the knives of the othercutting tools. Thus in Fig. 5, it will be seenthat the middle cuttingtool has its spiral knives 27' coursing oppositely to the spiraldirections of the top and bottom cutting tools. Under this arrangement,the raised portions on the overlay sheet may be attackedA froml oppositedirections with a slicing motion, so thatthey will be cleanly andaccurately cut or sliced oii'. Adjustably secured inthe framesBOVimmedately in advance of each cutting tool,l is a brush 33 whichengages the overlay sheet as it travels around with the cylinder andeliminates substantially all the air from under the overllay sheet.These brushes make the overlay sheet hug the cylinder tightly so thatthe cutting tools willucut oif only. the raised portions on the overlaysheet.

The `cylinder is driven` in one direction While each of theindependently adjustable cutting tools is driven in a ldirection oposite thereto. To accomplish lthis the axis of them/cylinder isprovided with a large gear 34 which drives the intermediate gears 35 ofthe cutting tools arel driven. The cylin- Y der is driven at a slowspeed while through this system of gearinvfthe cutting tools are drivenat a fairly hiih speed.

In making-ready the printing form in' the the printing form are verypronounced, it maybe necessary to make two or more overlay sheets inorder to compensate fully for all of the inequalities of pressure.

While I have illustrated and described the preferred form ofconstruction for carrying..y my inventioninto effect, this iscapable ofvariation and modication without depart ing from 'the spirit' oftheinvention. I, therefore, do'not'wish to be limited to the lprecisedetails of construction set forth, lbut desire toA availfmyself of suchvariations and modifications as come within the scope J of the appendedclaims.l

100 through which gears 36 attached to the axes Having described myinvention, what I claim as new and desi-reto secu'reby Letters Patentis:

1. The herein described method of making-h ready printing forms whichconsists in ta ing the impressions of the form on the obverse side of animpression sheet capable of showing, where the impressions are tooheavy, raised portions on its reverse side; and 1n reduclng the raisedportions to corresponding superfine dimensions from the facef thereverse side.

impressions. on the obverse side are too heavy; and in 'reducing thel'aised formations to corresponding superfne [dimensions from the faceof the coating. A C

a. The herein deseribed method ef makin ready printing formswhich'consists in ta mg the impresslons on a. body 1n sheet form;

. coating.

such abody being characterized by having a reverse-side which willindicate by .raised formations where the impressions are too heavy; inattaching the body t-o a support with the 1'aised"for mations facingoutwardly'; and in Ireducing the raised formations by rapidly revolvingslicing knives to corresponding superine dimensions from th'e face ofthe reverse side. l i

4. The herein described method of makingready printing forms whichconsists in tak-v ing the impressions on a body in sheet form;

such la body being characterized by having a' coating on .its reverseside capable of showing byvraised formations where the impressions onthe obverse side are( too heavy; in attaching the body tov a supportwith the raised formations facing outwardly; and in reducing the raisedformations by rapidly revolving slicing knives to 'correspondingsuperfine dimensions from the face of the In testimonywhereof I havesigned my name to this s ecication.

SAMUEL NDR`EW MCFARLAND.

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